Multi-modality imaging systems may generate one or more functional images and one or more structural images. For example, a PET-CT system may generate a functional PET image and a structural CT image. One or more lesion locations may be determined accurately based on a registration of the functional image(s) and corresponding structural image(s). The images generated by a multi-modality imaging system may provide more detailed and reliable diagnostic information than that generated by a single-modality system (e.g., a CT system, a PET system, an MRI system, etc.). However, there may be an error in the reconstruction centers of a functional image and a structural image generated by a multi-modality imaging system. The error of reconstruction center may reduce registration accuracy. Therefore, it is desirable to correct the error of the reconstruction centers of the multi-modality imaging systems.